Audi A4 Avant 95-01 Service & Repair Manual

01-1

Motronic, On Board

Diagnostic (OBD)

On Board Diagnostic (OBD), technical

data

Equipment

Data is transmitted between the control module

and the VAS5051 tester or VAG1551 Scan Tool

(ST) via operating mode "Rapid Data Transfer".

DTC memory is designed for permanent

memory and is therefore not dependent on

voltage supply.

Display of stored DTCs occurs after initiation of

display mode Page 01-15 .

DTC memory must be erased after malfunction

is repaired Page 01-15 .

Important:

Readiness code must be re-generated after

every time DTC memory is erased Page 01-

82 .

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01-2

If the ECM recognizes malfunctions that lead to

a degradation of emissions values, it indicates

them by lighting the Malfunction Indicator Lamp

(exhaust warning lamp -K83-). Clarification of

this lamp Page 01-3 .

"E-Gas"-relevant malfunctions are also

indicated in the instrument cluster by the

warning lamp for Electronic Power Control

("EPC warning lamp").

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01-3

Malfunction Indicator Lamp (MIL),

significance

If the ECM recognizes malfunctions that lead to a

degradation of emissions values, it indicates

them by lighting the Malfunction Indicator Lamp

for exhaust.

Installation position of exhaust MIL

Note:

The Malfunction Indicator Lamp (MIL) can blink or remain lit continuously.

DTC memory should be checked in both cases Page 01-15 .

Blinking: There is a malfunction that causes damage to the catalytic

converter in this driving condition (e.g. combustion misfire). In this

case, vehicle must only be driven at reduced power!

Continuously lit: There is a malfunction that causes increased

emissions. Check DTC memory for Motronic ECM and automatic

transmission (if installed).

If there are driveability problems or if there is a customer complaint

and the exhaust MIL is not lit, DTC memory must be checked. There

may be DTCs stored that do not cause the exhaust MIL to light up

immediately, but only if malfunction is recognized again after repeated

engine starts.

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01-4

Malfunction Indicator Lamp (MIL),

checking

Special Tools and Equipment

VAG1594A

VAG1598/31

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01-5

Function test of warning lamp

- Switch ignition on.

Warning lamp for On Board Diagnostic

(Malfunction Indicator Lamp -MIL-) must

light up

A - Warning lamp for On Board Diagnostic

(Malfunction Indicator Lamp -MIL-) does not

light up

- Connect VAG1598/31 test box at wiring harness

to ECM, do not connect ECM Page 24-17 .

- Bridge sockets 1 and 47 of test box.

- Switch ignition on.

Warning lamp must light up.

If warning lamp does not light up:

- Switch ignition off.

- Remove instrument cluster:

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Repair Manual, Electrical Equipment, Repair

Group 90, Instrument cluster, removing and

installing

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01-6

- Check the following wire connection for open

circuit and short circuit to B+:

Test box

VAG1598/31

Socket

Instrument cluster

Terminal

47 Electrical Wiring Diagrams,

Troubleshooting & Component

Locations binder

- Repair open circuit or short circuit if

necessary.

If wire connection is OK:

- Replace Engine Control Module (ECM) Page

24-21 .

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01-7

B - Warning lamp for On Board Diagnostic

(Malfunction Indicator Lamp -MIL-) remains lit

constantly

- Check DTC memory of Engine Control Module

(ECM) Page 01-15 .

If no DTCs are stored:

- Connect VAG1598/31 test box at wiring harness

to ECM, do not connect ECM Page 24-17 .

- Remove instrument cluster:

Repair Manual, Electrical Equipment, Repair

Group 90, Instrument cluster, removing and

installing

- Check the following wire connection for short

circuit to Ground (GND):

Test box

VAG1598/31

Socket

Instrument cluster

Terminal

47 Electrical Wiring Diagrams,

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Troubleshooting & Component

Locations binder

- Repair short circuit if necessary.

If wire connection is OK:

- Replace Engine Control Module (ECM) Page

24-21 .

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01-8

Safety precautions

If special testing equipment is required during

road test, note the following:

WARNING!

Scan tools and testing devices must always

be secured on the rear seat and operated

from there by a second person.

If a scan tool or testing device were to be

operated from the passenger seat and there

were an accident involving activation of the

passenger-side airbag, the person seated

there could be seriously injured.

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01-9

VAS 5051 vehicle diagnostic, testing

and information system orVAG1551

Scan Tool (ST), connecting and

selecting functions

Test requirements:

Fuses for engine electronics OK

Electrical Wiring Diagrams, Troubleshooting &

Component Locations binder

Fuel Pump (FP) OK, checking Page 24-

49 .

Battery voltage at least 12.7 V

Ground (GND) connections at engine and

transmission OK

Procedure

Note:

- Connect VAS5051 tester to vehicle with VAS5051/1 diagnostic wire.

Alternately, VAG1551 Scan Tool (ST) can also be attached using

VAG1551/3B cable.

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Data Link Connector (DLC) is located in front left knee bolster.

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01-10

WARNING!

Observe safety precautions Page 01-8 .

Note:

The following description only explains

implementation of On Board Diagnostic using

VAG1551 Scan tool.

When using the VAS5051 tester, observe the

tester's instructions for use

V

.A.G - ON BOARD DIAGNOSTIC HELP

1 - Rapid data transfer 1)

2 - Blink code output 1

)

Indicated on display:

1)

Operating modes 1 and 2 are displayed alternately

Note:

If nothing appears in display:

- Perform troubleshooting procedure after "troubleshooting procedure leak

test":

Electrical Wiring Diagrams, Troubleshooting & Component Locations

binder

Depending on desired function Table "Selectable functions", page

Page 01-14 :

- Switch ignition on.

or

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- Start engine.

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01-11

- Press -Print- button to turn on Scan Tool (ST)

printer. Indicator lamp in button must light up.

- Press button 1 to select "Rapid data transfer"

operating mode 1.

Rapid data transfer HELP

Insert address word XX

When indicated on display:

Note:

The address word 00 initiates the automatic test sequence, i.e. it results in

a DTC check on all OBD capable systems in the vehicle via rapid data

transfer.

- Press buttons -0- and -1- to select "engine electronics" and press -Q-

button to confirm input.

3B0907551BA 2.8l V6/5V G 0003

Codin

g

07251 WSC 12345

VAG1551 Scan Tool (ST) display indicates control module identification,

e.g.:

Note:

Control module identification can be printed by pressing the PRINT key of

the VAG1551 scan tool.

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01-12

Control module identification (example)

3B0907551

BA

part number; allocation

Parts Catalog

2.8 L

Engine displacement

V6/5V

Construction style of engine (V

engine, 6 cylinder, 5 valves)

"G" i.e. no

indication

Vehicle with or without cruise

control system

0003

Data version (software

version) of control module

Coding

07251

Control module coding

WSC 12345

Factory identification of

VAG1551, with which the last

coding was performed

-

Press button.

Rapid data transfer HELP

Select function XX

Indicated on display (function selection):

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01-13

Notes:

It will be possible to display the control module

identification again after pressing buttons -0-

and -1- to select "Check Control Module

Versions" and confirming with the -Q- button.

Rapid data transfer HELP

Control module does not answer

When indicated on display:

Rapid data transfer HELP

K-wire not switchin

g

to Ground

- Perform troubleshooting procedure after "troubleshooting procedure leak

test":

Electrical Wiring Diagrams, Troubleshooting & Component Locations

binder

Rapid data transfer HELP

K-wire not switchin

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to B+

Rapid data transfer HELP

Error in communication link

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01-14

Selectable functions

VAS 5051 vehicle diagnostic, testing and information

system or VAG1551 Scan Tool (ST)

Ignition

on,

engine

off

Engine running

at idle

Vehicle in drive

mode

page

Address words

01 Engine electronics Yes Yes Yes Page

01-9

00 Automatic test sequence Yes Yes Yes Page

01-11

Functions

01 Check Control Module Versions Yes Yes Yes Page

01-13

02 Check DTC Memory No Yes Yes Page

01-15

03 Output Diagnostic Test Mode (DTM) Yes No No Page

01-56

04 Basic Setting Yes Yes Yes Page

01-66

05 Erase DTC Memory Yes Yes Yes Page

01-15

06 End Output Yes Yes Yes Page

01-17

07 Code Control Module Yes No No Page

01-71

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08 Read Measuring Value Block Yes Yes Yes Page

01-74

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01-15

Check DTC Memory (function

02) and Erase DTC Memory

(function 05)

- Connect VAS5051 tester or VAG1551 scan tool

and select the control module for engine

electronics using "address word" 01 Page 01-

9 .

Engine must run at idle for this.

Note:

If engine doesn't start, crank engine using starter

for at least 5 seconds. Do not switch ignition off

afterward under any circumstance.

Rapid data transfer HELP

Select function XX

When indicated on display:

- Press buttons -0- and -2- to select "Check DTC memory" and press -Q-

button to confirm input.

No DTC reco

g

nized

When indicated on display:

or

-

Press button.

X DTC reco

g

nized

When indicated on display:

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Audi A4 Avant 95-01 Service & Repair Manual

Audi A4 Avant 95-01 Service & Repair Manual

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